The present invention relates, in general, to cyclone separators, particularly those utilized in fluidized bed reactors, and in particular to a new and useful integrated cylindrical cyclone plus loopseal combination which also includes immersed heat exchangers for removing heat from the structure.
The use of heat exchangers in the walls of a cyclone separator is known, for example, from U.S. Pat. No. 4,944,250. Also, see U.S. Pat. No. 4,746,337 for a cyclone separator having water-steam cooled walls.
In the field of power plants and fluidized chemical reactors, loopseals or fluoseals are used with circulating fluidized beds (CFB's) in order to return solids collected by cyclone separator, to the combustor of the CFB. The fluoseals are refractory-lined carbon steel vessels. These loopseals are supported independently from the pressure parts of the combustor.
The inventors of the present application are also co-inventors in a co-pending U.S. patent application Ser. No. 08/203,785 filed Mar. 1, 1994 and not prior art to the present application. Ser. No. 08/203,785 which is entitled INTEGRAL WATER COOLED FLUOSEAL, is relevant to understand the present application, in that it discloses a cyclone separator having heat exchanger components therein.
Another co-pending application having the inventors of the present application as co-inventors, is U.S. patent application Ser. No. 08/187,197 filed Jan. 24, 1994 entitled INTEGRAL CYLINDRICAL CYCLONE AND LOOPSEAL. This application, which is incorporated here by reference, discloses an arrangement for separating solids from gases in a cyclone separator by providing an annular partition wall in a cylindrical cyclone housing for separating inner and outer solids containing spaces. Both spaces receive fluidizing air, with respective underflow and overflow passages forming a passageway for separated solids to be returned to the fluidized bed reactor, from the cyclone separator. A primary advantage is the incorporation of both a seal and cyclone structure within a substantially cylindrical enclosure, eliminating the usual lower, inwardly conical section of a conventional cyclone separator, as well as the separate fluoseal structure used with conventional separators.
In CFB boiler systems with high levels of steam superheat and/or reheat, a certain amount of superheat type heat exchanger surface must be placed somewhere within the combustor or the solids recirculation loop. Existing methods to achieve this include: (a) the addition of heat transfer panels within the combustor; (b) the use of a separate immersed heat exchanger situated downstream of the loopseal and upstream of the combustor; and (c) the use of a heat exchanger as described in (b), except that it is formed as an integral portion of the combustor enclosure.